Charging method and network system thereof, packet data network gateway and charging system thereof

ABSTRACT

A charging process method, relating to communication network, is disclosed according to embodiments of the present invention. The method includes receiving a charging request containing a type of a second method when the method for a user equipment to access a packet data network gateway has been changed from a first method to the second method; performing, based on the charging request, charging control over the used service units in a charging mode corresponding to the first method for the user equipment to access the packet data network gateway and reserving service units for the charging session for the second method based on a charging mode corresponding to the second method for the user equipment to access the packet data network gateway. A network system, a packet data network gateway and a charging system are provided according to embodiments of the present invention accordingly. Embodiments of the present invention can be applicable to a charging process in a situation when the method for a user equipment to access the packet data network gateway changes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/710,235 filed on Feb. 22, 2010, which is a continuation ofInternational Application No. PCT/CN2008/071820, filed on Jul. 30, 2008,which claims priority to Chinese Patent Application No. 200710142034.4,filed on Aug. 20, 2007, all of which are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to communication network field, and morespecifically to a charging process method and a network system thereof,a packet data network gateway and a charging system thereof.

BACKGROUND

Currently, with a further development of the communication networktechnology, operators are able to provide users with various services.For the service provided by the operators, user equipments (UE) mayemploy different access methods. Therefore, the operator may adoptdifferent charging modes based on characteristics of different accessmethods. The charging modes generally include flow-based charging,time-based charging or event-based charging, etc. For instance, in aSystem Architecture Evolution (SAE) core network, if the UE adoptsEvolved UMTS Terrestrial Wireless access Network (E-UTRAN) as an accessmethod, the operator may adopt a flow-based charging mode. If the UEconnects via a Wireless Local Area Network (WLAN), the operator maycharge the user with a time-based charging mode.

A conventional charging framework for the SAE architecture may adoptE-UTRAN access method and WLAN access method.

For E-UTRAN access method, collection points for on-line charging aredeployed at a Packet Data Network Gateway (PDN GW). The collectionpoints gather from the PDN GW associated charging information about thebearer layer and report the charging information to an Online ChargingSystem (OCS) for charging control, such as fee deduction.

For WLAN access method, the collection points for on-line charging maybe deployed at an evolved Packet Data Gateway (ePDG), PDN GW or AAAserver (3GPP AAA Server). These collection points gather charginginformation about the bearer layer associated with the WLAN and reportthe charging information to the OCS for charging control, such as feededuction.

During researches and practices regarding the conventional art, it isdiscovered that according to conventional art, charging in the case ofdifferent access techniques is separately controlled in differentcharging architectures. When the user uses the service, if the accessmethod changes, a current charging session has to be interrupted andswitched to another charging architecture for charging control.Therefore, charging continuity in the case of a handover of the accessmethod cannot be achieved.

SUMMARY

A charging process method, a network system, and a packet data networkgateway are provided according to embodiments of the present invention.The charging process method, the network system, and the packet datanetwork gateway allow for continuous charging when the method for a userequipment to access the PDN GW changes.

To solve the foregoing problem, technical solutions are presented belowaccording to the present invention.

A charging process method is provided according to an embodiment of thepresent invention. The method includes:

monitoring if there is any change in a method for a user equipment toaccess a packet data network gateway; and

sending to a charging system a charging request containing a type of asecond method when it is detected that the method for the user equipmentto access the packet data network gateway has been changed from a firstmethod to the second method.

A charging process method is provided according to an embodiment of thepresent invention. The method includes:

receiving a charging request containing a type of a second method when amethod for a user equipment to access a packet data network gateway hasbeen changed from a first method to the second method; and

performing, based on the charging request, charging control over theused service units in a charging mode corresponding to the first methodfor the user equipment to access the packet data network gateway andreserving service units for the charging session for the second methodbased on a charging mode corresponding to the second method for the userequipment to access the packet data network gateway.

A network system is provided according to an embodiment of the presentinvention. The network system includes a packet data network gateway,configured to send a charging request containing a type of a secondmethod after the packet data network gateway detects that the method forthe user equipment to access the packet data network gateway is changedfrom a first method to the second method; and a charging system,configured to receive the charging request sent by the packet datanetwork gateway; perform, according to the charging request, chargingcontrol over the used service units in a charging mode corresponding tothe first method for the user equipment to access the packet datanetwork gateway; and reserve service units for a charging session forthe second method based on a charging mode corresponding to the secondmethod for the user equipment to access the packet data network gateway.

A packet data network gateway is provided according to an embodiment ofthe present invention. The packet data network includes a detectingunit, configured to monitor if there is any change in a method for auser equipment to access the packet data network gateway; and a chargingrequest unit, configured to send to the charging system the chargingrequest containing the type of the second method when it is detectedthat the method for the user equipment to access the packet data networkgateway has been changed from the first method to the second method.

A charging system is provided according to an embodiment of the presentinvention. The charging system includes a receiving unit, configured toreceive the charging request sent by the packet data network gateway,wherein the charging request contains the type of the second method forthe user equipment to access the packet data network gateway; and aprocessing unit, configured to perform, based on the charging requestreceived by the receiving unit, charging control over used service unitsin a charging mode corresponding to the first method for the userequipment to access the packet data network gateway and reserve serviceunits for the charging session for the second method based on a chargingmode corresponding to the second method for the user equipment to accessthe packet data network gateway.

As can be seen from the above technical solutions, in the conventionalart, charging control in the case of different access techniques isperformed separately in different charging architectures. When ahandover of the access method is performed, the charging continuityduring the handover of the access method cannot be achieved. However,the technical solutions according to the embodiments of the presentinvention take full advantage of the centralized control functions ofthe PDN GW and utilize the PDN GW to detect if the method for the UE toaccess the PDN GW has been changed. When it is detected that the methodfor the UE to access the PDN GW has been changed from a first method toa second method, the charging system sends a charging request containinga type of the second method. The charging system performs, based on thecharging request, charging control over the used service units under acharging mode corresponding to the first method for the UE to access thePDN GW and reserves service units for the charging session of the secondmethod based on the charging mode corresponding to the second method forthe UE to access the PDN GW. Therefore, charging continuity during thehandover of the method for the UE to access the PDN GW can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a charging architecture combining differentaccess methods according to an embodiment of the present invention;

FIG. 2 is a flowchart of a charging process method according to anembodiment of the present invention;

FIG. 3 is a flowchart of a charging process method after the UE sets upan E-UTRAN connection according to an embodiment of the presentinvention;

FIG. 4 is a flowchart of a charging process method when handover isperformed from the E-UTRAN to the WLAN according to an embodiment of thepresent invention; and

FIG. 5 is a block diagram of a network system according to an embodimentof the present invention.

DETAILED DESCRIPTION

A charging process method is provided according to an embodiment of thepresent invention. The method allows for charging continuity when themethod for the user equipment to access the PDN GW changes.

Before introducing the charging process method of the present invention,a charging architecture combining different access methods according toan embodiment of the present invention is first introduced. Referring toFIG. 1, a block diagram of a charging architecture combining differentaccess methods according to an embodiment of the present invention isillustrated.

The charging architecture in FIG. 1 may guarantee charging continuitywhen a user equipment adopts a different access method to access the PDNGW. FIG. 1 includes an E-UTRAN access network, a Mobile ManagementEntity (MME), a Serving Gateway (Serving GW), a Home Subscriber Service(HSS), a Packet Data Network Gateway (PDN GW), an Online Charging System(OCS), a serving network (e.g., IMS network), a WLAN access network, anAAA server (3GPP AAA Server), wherein the WLAN access network includes aWAG and an ePDG. In FIG. 1, the collection points for online chargingare collectively deployed at the PDN GW. Charging information about thebearer layer is gathered from the PDN GW and is reported to the OCS forcharging control.

It should be noted that FIG. 1 is only an example where a handoverbetween E-UTRAN and WLAN is performed. The handover between other accessmethods, such as from E-UTRAN access to 2G/3G access, can also becontemplated.

The SAE may support various access methods, including the secondgeneration mobile communication network (2G) IP access/the thirdgeneration mobile communication network 3G IP access, E-UTRAN IP accessand non-3GPP IP access. The non-3GPP IP access may be categorized into atrusted type and an untrusted type. The untrusted non-3GPP IP accessperforms access through an ePDG. The WLAN access belongs to theuntrusted non-3GPP IP access. Meanwhile, the SAE supports a handover ofthe user equipment among various access methods. For example, in FIG. 1,a handover of the user equipment from E-UTRAN to WLAN is illustrated.

A brief introduction to the main function entities in the SAEarchitecture involved in FIG. 1 is provided below.

The Mobility Management Entity (MME) mainly handles mobility managementincluding storing the context of UE control plane such as user ID(UEID), user status, tracking area (TA), performing mobility management,performing authentication and key management, encrypting signaling,protecting integrity, managing and allocating temporary user ID, etc.The MME is further responsible for controlling signaling interaction.The MME may interact with a Home Subscriber Server (HSS) and may beresponsible for user ID authentication.

The Serving GW is mainly responsible for handling user plane dataincluding routing and forwarding data, compressing data header, andstoring the context of UE user plane. The context of UE user planeincludes basic IP bearer information, routing information, etc. Afterthe Serving GW establishes a bearer with the base station via the MME,the Serving GW is responsible for relaying and routing the user datapacket.

The PDN GW is mainly responsible for handling user plane betweensystems, including handling switching between the user planes ofdifferent access systems, routing and forwarding data, collectingaccount data, implementing the function of the gateway for connecting tothe Package Data Network (PDN). In SAE architecture, the PDN GW isresponsible for core control. The operator controls various accessmethods via the PDN GW. Different accesses connect into the PDN GW viatheir respective access gateway device. As to 2G/3G access, a ServingGPRS Supporting Node (SGSN) is used for access to the Serving GW andthus connecting to the PDN GW. For E-UTRAN access, the Serving GW isused for connecting to the PDN GW. For WLAN access, the ePDG is used forconnecting to the PDN GW. The centralized control function of the PDN GWallows the operator to manage different access techniques for connectingtowards the mobile IP network.

The ePDG is mainly used in untrusted non-3GPP IP access. The untrustednon-3GPP IP access connects to the PDN GW via the ePDG. By interactingwith the 3GPP AAA server, the ePDG authenticates and authorizes theuntrusted non-3GPP IP access.

A charging process method is provided according to an embodiment of thepresent invention. The method introduces an additional parameter“SAE-Information” in the service information (Service-Info) of acharging request (Credit Control Request, CCR) and a charging requestanswer (Credit Control Answer, CCA). The SAE-Information parameter isillustrated in Table 1. In Table 1, the type of access method“SAE-RAT-Type” and the handover time “SAE-RAT-Handover-Time” are newlyadded according to the present embodiment.

TABLE 1 Parameter Application Description SAE-Charging-ID OC (optionalto the PDP context identifier used to operator) identify this PDPcontext in different charging records created by PDN GW. SAE-PDP-Type OM(mandatory to PDP type, i.e. IP, PPP, or the operator) IHOSS: OSP.PDP-Address OC (optional to the This field holds the PDP address ofoperator) the served IMSI, i.e. IPv4 or IPv6. This parameter shall bepresent except when both the PDP type is PPP and dynamic PDP addressassignment is used. SAE-GPRS-Negotiated- OC (optional to the This fieldholds the QoS profile QoS-Profile operator) applied by PDN GW.Served-IMSI M (Mandatory) IMSI of the served party. MME-Address M(Mandatory) Identify the address of MME Serving GW-Address M (Mandatory)Identify the address of Serving GW PDN GW-Address M (Mandatory) Identifythe address of PDN GW ePDG-Address OC (Optional to the Identify theaddress of ePDG operator) SAE-IMSI-MCC-MNC OC (Optional to the Thisfield holds the MCC and MNC operator) extracted from the user's IMSI(first 5 or 6 digits, as applicable from the presented IMSI). SAE-PDN OC(Optional to the This field holds the MCC-MNC of GW-MCC-MNC operator)the network the PDN GW belongs to. SAE-NSAPI OC (Optional to the Thisfield Identifies a particular PDP operator) context for the associatedPDN and MSISDN/IMSI from creation to deletion. Called-Station-ID OC(Optional to the This field contains the identifier of operator) theaccess point (APN) the user is connected to. SAE-Session-Stop- OC(Optional to the This field indicates to the OCS that Indicatoroperator) the last PDP context of a session is released and that the PDPsession has been terminated. CG-Address OC (Optional to the This fieldholds the Charging operator) Gateway IP address. SAE-Selection-ModeUE-only, UE/NW or NW-only 3GPP-Charging- OC (Optional to the This fieldcontains the charging Characteristics operator) characteristics for thisPDP Context received in the Create PDP Context Request MessageCharging-Rule-Base-Name OC (Optional to the This field indicates thename of a operator) pre-defined group of PCC rules residing at the PCEF.It may occur several times within the PS Information field.SAE-User-Location-Info OC (Optional to the Tracking Area Identifieroperator) SAE-RAT-Type OC (Optional to the This field identifies thetype of operator) wireless access technique, which may be 3G, 2GE-UTRAN, WLAN, Wimax, etc SAE-RAT-Handover-Time OC (Optional to the Thisfield holds the handover time operator) that the method for accessingthe PDN GW changes.

FIG. 2 is a flowchart of a charging process method according to anembodiment of the present invention. The method includes the followingsteps.

401: The PDN GW receives a service data request from the UE.

402: The PDN GW sends an initial charging request to the OCS. Theinitial charging request includes a type of an access method for the UEto access the PDN GW and/or requested service units in the case of thisaccess method.

403: The OCS returns an initial charging request answer to the PDN GW.The initial charging request answer includes the service units allocatedfor the service in the case of this access method for the UE to accessthe PDN GW and a new condition for triggering an intermediate chargingrequest is set, wherein the condition is that the access method for theUE to access the PDN GW changes.

The access method for the UE to access the PDN GW is determined to bechanged when a change in the wireless access method is detected(Trigger-Type=CHANGE_IN_RAT) and/or when a change in the Serving node isdetected

(Trigger-Type=Serving_Node_Change). The wireless access method isdetermined to be changed when a handover among the WLAN, E-UTRAN and2G/3G wireless accesses is performed. The serving node may be a ServingGW or an ePDG.

404: The PDN GW monitors if there is any change in the method that theUE connects to the PDN GW after the PDN GW receives an initial chargingrequest answer.

405: After the PDN GW detects that the method for the UE to access thePDN GW has been changed from a first method to a second method, the PDNGW sends an intermediate charging request to the OCS. The intermediatecharging request includes the service units used by the UE in the caseof the first method, i.e., the previous method for accessing PDN GW, andincludes a type of the second method, i.e., the new method for accessingPDN GW.

In addition, the intermediate charging request may further include theservice units requested by the UE in the case of the new method foraccessing PDN GW and the handover time of switching to the new methodfor accessing PDN GW.

406: The OCS extracts from the intermediate charging request the serviceunits used by the UE in the case of the previous method for accessingthe PDN GW, performs a charging control, and reserves service units fora service in the case of the new method for accessing the PDN GW, i.e.,determines the service units to be allocated.

The OCS performs charging control based on the service units which havebeen used in the case of the previous method for accessing PDN GW and isindicated in the intermediate request. For instance, the chargingcontrol may include fee deduction, other operation, etc. The OCS thendetermines service units to be allocated for the service in the case ofthe type of the new method for accessing PDN GW according to the type ofthe new method for accessing PDN GW in the charging request. When thecharging mode varies with a different access method, the service unitsneed to be converted based on the rating, for instance, from flow-basedmode to time-based mode. It should be noted that if the intermediatecharging request does not contain the service units used in the case ofthe previous method for accessing PDN GW, it is generally believed thatthe amount of the used service units is zero.

If the intermediate charging request further includes the service unitsrequested in the case of the new method for accessing PDN GW, the OCSdetermines service units to be allocated for a service in the case ofthe new method for accessing PDN GW based on the requested serviceunits, the used service units in the case of the previous method foraccessing PDN GW and the account balance associated with the UE in thedata base. If it is discovered, after the service in the case of theprevious method for accessing PDN GW was charged for, that the remainingservice units obtained by subtracting the used service units in the caseof the previous method for accessing PDN GW from the UE's user accountare less than the requested service units, a reverse calculation isconducted on the remaining service units according to the operator'scharging policy for the service. Then, the quotas of the service unitsthat can be actually allocated are determined. Or, if it is discoveredthat the remaining service units obtained by subtracting the usedservice units in the case of the previous method for accessing PDN GWfrom the UE's user account are not sufficient for supporting the UE touse the service continuously, no more service units will be allocated toUE and the service serving the UE will be interrupted.

If the charging request further includes the handover time when ahandover of the method for accessing PDN GW is performed, the OCS takesthis handover time as a reference point for performing a chargingcontrol over the service in the case of the pervious method foraccessing PDN GW and for determining the service units to be allocatedin the case of the new method for accessing the PDN GW.

407: The OCS returns an intermediate charging request answer to the PDNGW. The intermediate charging request answer includes the service unitsto be allocated in the case of the new method for accessing PDN GW.

408: The PDN GW delivers service data in the case of the new method foraccessing PDN GW.

409: After the service serving the UE is completed, the PDN GW sends afinal charging request to the OCS. The final charging request includesthe service units used by the user in the case of the new method foraccessing PDN GW.

410: The OCS extracts from the final charging request the service unitsused by the user in the case of the new method for accessing PDN GW andperforms charging control.

It should be noted that online charging procedure is illustrated as anexample of the charging process method according to the presentembodiment. However, the present embodiment is not limited in thisrespect. This solution may also be applicable to an offline chargingprocedure. Offline charging has no effect on the process of using theservice. When the PDN GW reports the charging request to an offlinecharging system, the charging request may not need to include therequested service units and the offline charging system may not need todetermine the service units to be allocated to the service serving theUE. During offline charging, the PDN GW may also monitor if there is anychange in the method for the UE to access PDN GW. When the PDN GWdetects that the method for the UE to access PDN GW changes, the PDN GWsends an intermediate charging request to the offline charging system.The intermediate charging request includes service units used by the UEin the case of the previous method for accessing PDN GW and the type ofthe new method for accessing PDN GW. After the UE terminates the servicein the new method of accessing the PDN GW, the PDN GW sends a finalcharging request to the offline charging system. The final chargingrequest includes the service units used by the user in the case of thenew method for accessing PDN GW. The offline charging system may performcharging control based on the received used service units in the case ofthe two methods for accessing PDN GW.

FIG. 3 is a flowchart of a charging process method after the UE sets upan E-UTRAN connection according to an embodiment of the presentinvention.

501: The UE sends uplink data.

After the UE sets up an E-UTRAN connection, the UE sends the uplinkdata.

The procedure for the UE setting up the E-UTRAN connection is describedas follows. The UE sends an Attach request to the MME via eNodeB andperforms authentication at HSS via the MME. After receiving the Attachrequest, the MME sends a Create default bearer request to the PDN GW viathe Serving GW and receives a Create default bearer response from thePDN GW. Then, the MME sends an Attach response to the eNodeB. The eNodeBsubsequently sends a Create wireless bearer layer request to the UE.When receiving a Create wireless bearer layer response from the UE, theeNodeB returns a bearer layer setup complete response to the MME.

502: After the PDN GW receives a service request sent by the UE, the PDNGW sends an initial charging request (CCR) to the OCS. The initialcharging request includes a type of the access method indicated by“SAE-Information” (e.g.,

SAE-RAT-Type=E-UTRAN) and requested service units (e.g., RSU=10M).

503: After the OCS receives the initial charging request, the OCSperforms online charging control and determines the service units to beallocated (e.g., GSU=10M) based on the account balance associated withthe UE in the data base.

504: The OCS sends an initial charging request answer (e.g., CCA) to thePDN GW. The initial charging request answer includes the allocatedservice units (e.g., GSU=10M) and a new condition for triggering theintermediate request is set when the method for the UE to access PDN GWchanges (Trigger-Type=CHANGE_IN_ART).

505: The PDN GW may forward the uplink data and monitor if there is anychange in the method for the UE to access the PDN GW after the PDN GWreceives the initial charging request answer.

506: The PDN GW receives the uplink data.

After the PDN GW receives an update bearer layer request from the MME,the PDN GW sends an update bearer layer request answer to the MME.Meanwhile, the PDN GW receives the downlink data.

507: The PDN GW sends an intermediate charging request (CCR) to the OCS.The request includes a type of the access method indicated by“SAE-Information” (e.g., SAE-RAT-Type=E-UTRAN) and requested serviceunits (e.g., RSU=15M).

508: After the OCS receives the intermediate charging request, the OCSperforms online charging control and determines the service units to begranted (e.g., GSU=15M) based on the account balance associated with theUE in the database.

509: The charging system returns an intermediate charging request answer(CCA) to the PDN GW. The request includes the service units to begranted (GSU=15M).

510: The PDN GW sends the downlink data to the UE.

FIG. 4 is a flowchart of a charging process method when a handover isperformed from the E-UTRAN to the WLAN according to an embodiment of thepresent invention. The method includes the following steps.

601: The UE accesses the WLAN. The PDN GW detects a change of thewireless access method.

A handover of the UE from E-UTRAN to WLAN can be performed while theuplink data and the downlink data are under transmission and thecharging session between the PDN GW and the OCS is going on. Thehandover procedure is performed as follows. The UE performsauthentication at 3GPP AAA server and HSS via the ePDG. The HSS thenupdates routing information and the ePDG sends an update bearer layerrequest to the PDN GW and receives an update bearer layer request answerfrom the PDN GW. Then, a data tunnel is set up between the ePDG and thePDN GW and a data tunnel is also set up between the ePDG and the UE.Thus, transmission of uplink data and downlink data can be achievedbetween the UE and the PDN GW. In other words, after the wireless accessmethod changes, the UE may now connect to the PDN GW via ePDG, whichwould otherwise connect to the PDG GW via the Serving GW. Meanwhile, thePDG GW detects that the wireless access method has been changed.

602: The PDG GW sends an intermediate charging request (CCR) to the OCS.The charging request may include a type of the service access methodindicated by “SAE-Information” (e.g., SAE-RAT-Type=WLAN) and a handovertime when a handover of the method for accessing PDN GW is performed,e.g.

SAE-RAT-Handover-Time=200708090830 (08:30, Aug. 9, 2007). The requestmay also include the used service units (USU=3M) in theMultiple-Services-Credit-Control parameter (MSCC 1) in the case ofE-UTRAN access, reason for reporting used service units (ReportingReason=RATING_CONDITION_CHANGE), reason for triggering reporting usedservice units (Trigger-Type=CHANGE_IN_RAT). For WLAN access method, therequested service units in MSCC2 is RSU=10 mins.

603: The OCS performs an online charging control, performs chargingcontrol over the original wireless access method, and determinesallocated service units for the new access method.

After the OCS receives the intermediate charging request (CCR), the OCSextracts used service units (USU) in the case of E-UTRAN access andperforms charging control over the service in the case of E-UTRANaccess. If the used service units (USU) are less than the GSU allocatedto the service previously, the UE will be compensated. That is, theservice units of GSU minus USU are compensated to the UE. The OCSfurther extracts information such as UE's new wireless access method(SAE-RAT-Type=WLAN) and the requested service units RSU in the MSCC2 inthe case of WLAN access and determines the service units to be allocatedto the service in the case of WLAN access. As the charging modes forE-UTRAN access and the WLAN access are different, that is, the chargingmode for the E-UTRAN access is flow-based while the charging mode forWLAN access is time-based, there is a need to convert the service unitsfrom flow-based charging mode to time-based charging mode based on therating. The OCS performs charging control over the service in the caseof the original access method and allocates the service units for theservice in the case of the new access method based on reference pointaccording to the handover time. The handover time refers to the timewhen a handover of the method for accessing PDN GW is performed. Itshould be noted that flow-based and time-based charging modes areillustrated as examples of the charging mode. Alternatively, thecharging can also be performed on an event basis.

604: The OCS sends an intermediate charging request answer (CCA) to thePDN GW. The intermediate charging request answer includes the serviceunits determined to allocated in the MSCC2 in the case of the WLAN(e.g., GSU=10 mins).

605: The PDN GW forwards the service data (uplink data or downlinkdata).

606: After the service serving the UE is completed, the PDN GW sends afinal charging request (CCR) to the OCS. The final charging requestincludes the service units used by the user (e.g., USU=10 mins) in thecase of the WLAN access after a handover of the access method.

607: The OCS extracts from the final charging request (CCR) the serviceunits used by the user in the case of WLAN access and performs chargingcontrol.

It should be noted that the above description takes a handover from theE-UTRAN to WLAN as an example. The principle may also be applied to thehandover from WLAN to E-UTRAN.

Further, as mentioned before, the PDN GW may monitor if there is anychange in the method for UE to access the PDN GW. The access method forthe UE to access the PDN GW is determined to be changed when a change inthe wireless access method is detected and/or a change in the Servingnode is detected. When a handover among the E-UTRAN, WLAN and 2G/3Gaccess methods is performed, the wireless access method is changed andthus the method for UE to access the PDN GW is changed. However, theserving node between the UE and the PDN GW might or might not bechanged. For instance, when a handover from the E-UTRAN to 2G/3G isperformed, the wireless access method is altered whereas the Serving GWconnecting to the PDN GW might be altered or might not be altered.Although the Serving GW connecting to the PDN GW is constant, thewireless data tunnel still needs to be re-established and the Serving GWneeds to notify the PDN GW since the access method is changed fromE-UTRAN to 2G/3G. Therefore, the PDN GW detects that the UE's accessmethod has been changed. The procedure is described as follows. The UEinteracts data with the PDN GW via Serving GW in the case of E-UTRANaccess. At that time, the UE is ready to connect to the 2G/3G networkenvironment. Then, the UE requests an access authentication from thetarget SGSN. The SGSN may perform authentication with the HSS viaServing GW/MME. After the authentication is passed, the UE may establisha data tunnel with the target SGSN and the target SGSN establishes adata tunnel with the Serving GW. Then, the Serving GW may update thedata tunnel with the PDN GW and send to the PDN GW informationindicating that the UE access method has been changed. Thus, the PDN GWdetects that UE wireless access method has been changed.

Another instance is that the wireless access method has not beenchanged, but the Serving GW connecting to the PDN GW has been changed.For example, during roaming, the UE may switch between different ServingGWs in the case of a same access method. In this case, the PDN GW mayconsider that the method for the UE to access PDN GW has been changed.The procedure is described as follows. The UE interacts data with thePDN GW via Serving GW. When the UE roams to the target Serving GWnetwork environment, the UE requests an access authentication from thetarget Serving GW. The target Serving GW may perform authentication withthe HSS via PDN GW. After the authentication is passed, the UE mayestablish a data tunnel with the target Serving GW. The target ServingGW may update the data tunnel with the PDN GW and send to the PDN GWinformation indicating that the access method for the UE to access PDNGW has been changed. Thus, the PDN GW detects that the method for the UEto access PDN GW has been changed.

It is appreciated by those skilled in the art that the entire or partialprocedures in the above embodiments can be implemented in hardware wheninstructed by programs. Such programs may be stored in a computer or ina readable storage media. The program, when executed, may include theprocedures described in the above various embodiments. The storage mediamay be a magnetic disc, an optic disc, a Read-Only Memory (ROM) or aRandom Access Memory (RAM), etc.

The above description introduces a charging process method according toan embodiment of the present invention. A network system, a packet datanetwork gateway and a charging system thereof are also providedaccording to embodiments of the present invention.

Referring to FIG. 5, a block diagram of a network system architectureaccording to an embodiment of the present invention is illustrated.

The network system illustrated in FIG. 5 includes a PDN GW 71 and acharging system 72.

The PDN GW 71 is configured to send a charging request containing thetype of a second method for the user equipment to access the PDN GW 71after the PDN GW 71 detects that the method for the user equipment toaccess the PDN GW 71 is changed from a first method to the secondmethod.

The charging system 72 is configured to receive the charging requestsent by the PDN GW 71. According to the charging request, the chargingsystem 72 performs charging control over the used service units in acharging mode corresponding to the first method for the user equipmentto access the PDN GW 71 and reserves service units for the chargingsession for the second method based on a charging mode corresponding tothe second method for the user equipment to access the PDN GW 71.

FIG. 5 illustrates a structure of the PDN GW 71. The PDN GW 71 includesa detecting unit 711 and a charging request unit 712.

The detecting unit 711 is configured to monitor if there is any changein the method for the UE to access the PDN GW 71. The detecting unit 711acquires from the charging system 72 a newly added condition fortriggering the charging request and monitors based on the acquiredcondition if there is any change in the method for the UE to access thePDN GW 71. The newly added condition is that the method for the userequipment to access the packet data network changes. Detecting, by thedetecting unit 711, that the method for the user equipment to access thePDN GW 71 has been changed from the first method to the second methodincludes detecting that the wireless access method has been changedand/or the serving node has been changed, wherein the user equipmentconnects to the PDN GW 71 via the Serving Node. The Serving Node is aServing GW or an ePDG.

The charging request unit 712 is configured to send to the chargingsystem 72 a charging request containing the type of the second methodfor the user equipment to access the PDN GW 71 after the detecting unit711 detects that the method for the user equipment to access the PDN GW71 has been changed from the first method to the second method. Thecharging request sent by the charging request unit 712 to the chargingsystem 72 further includes used service units in a charging modecorresponding to the first method for the user equipment to access thePDN GW 71 and/or the requested service units in a charging modecorresponding to the second method for the user equipment to access thePDN GW 71.

A structure of the charging system 72 is also illustrated in FIG. 5. Thecharging system 72 includes a receiving unit 721 and a processing unit722.

The receiving unit 721 is configured to receive the charging requestsent by the PDN GW 71, which contains the type of the second method forthe user equipment to access the PDN GW 71.

The processing unit 722 is configured to perform, based on the chargingrequest received by the receiving unit 721, charging control over theused service units in a charging mode corresponding to the first methodfor the user equipment to access the PDN GW 71 and reserves serviceunits for the charging session for the second method based on a chargingmode corresponding to the second method for the user equipment to accessthe PDN GW 71.

The charging system 72 further includes a condition setting unit 723configured to add a new condition for triggering the charging requestand send the condition to the PDN GW 71, wherein the added condition isthat the method for the user equipment to access the PDN GW 71 changes.

Overall, according to the conventional art, charging control in the caseof different access techniques is performed separately with differentcharging architectures. When a handover of the access method isperformed, the charging continuity during the handover of the accessmethod cannot be achieved. However, the technical solutions according tothe embodiments of the present invention take full advantage of thecentralized control functions of the PDN GW and utilize the PDN GW todetect if the method for the UE to access the PDN GW has been changed.When it is detected that the method for the UE to access the PDN GW hasbeen changed from a first method to a second method, the charging systemsends a charging request containing a type of the second method. Thecharging system performs, based on the charging request, chargingcontrol over the used service units in a charging mode corresponding tothe first method for the UE to access the PDN GW and reserves serviceunits for the charging session for the second method based on thecharging mode corresponding to the second method for the UE to accessthe PDN GW. Therefore, charging continuity during the handover of themethod for the UE to access the PDN GW can be achieved.

Further, the charging process method according to embodiments of thepresent invention may be applicable to both the online charging system(OCS) and the offline charging system. In the case that the method isapplied to the OCS, when it is detected that the method for the UE toaccess the PDN GW has been changed from the first method to the secondmethod, the charging request sent to the charging system may contain atype of the second method for the UE to access the PDN GW, the usedservice units in a charging mode corresponding to the first methodand/or the requested service unit in a charging mode corresponding tothe second method, and the time when the first method is changed to thesecond method. As a result, the charging process can be more refined andaccurate.

The above description is directed to a charging process method accordingto an embodiment of the present invention, a network system and acharging system thereof. It is appreciated by a person with ordinaryskill in the art that modifications may be made to the specificimplementation of the embodiments and the application fields inaccordance with the spirit and principle of the embodiments of thepresent invention. Therefore, the Specification shall not be construedas a limitation to the scope of the present invention.

1. A charging process method, comprising: receiving, from a chargingsystem by a packet data network gateway, a condition for triggering acharging request, the condition for triggering the charging requestcomprises that a method for a user equipment to access a packet datanetwork gateway changes; monitoring, by the packet data network gateway,if there is any change in the method for a user equipment to access thepacket data network gateway; and sending, by the packet data networkgateway, to the charging system the charging request containing a typeof a second method for the user equipment to access the packet datanetwork gateway when detecting that the method for the user equipment toaccess the packet data network gateway has been changed from a firstmethod to the second method.
 2. The method of claim 1, whereinmonitoring if there is any change in a method for a user equipment toaccess a packet data network gateway comprises: detecting at least oneof a change in a wireless access method and a change in a serving nodethrough which the user equipment accesses the packet data networkgateway.
 3. The method of claim 2, wherein: the change in the wirelessaccess method includes a handover among a Wireless Local Area Network,an Evolved UMTS Terrestrial Wireless Access Network and a secondgeneration mobile communication network/a third generation mobilecommunication network; and the serving node through which the userequipment accesses the packet data network gateway comprises a servinggateway or an evolved packet data gateway.
 4. The method of claim 3,further comprising: sending, by the packet data network gateway, aninitial charging request to the charging system, the initial chargingrequest including at least one of: a type of the first method for theuser equipment to access the packet data network gateway and requestedservice units in the case of the first method for the user equipment toaccess the packet data network gateway; wherein the condition fortriggering the charging request is contained in an initial chargingrequest answer sent from the charging system.
 5. The method of claim 3,wherein the charging request further comprises at least one of: usedservice units in a first charging mode corresponding to the first methodfor the user equipment to access the packet data network gateway;requested service units in a second charging mode corresponding to thesecond method for the user equipment to access the packet data networkgateway; and a handover time when the method for the user equipment toaccess the packet data network gateway is switched from the first methodto the second method.
 6. A charging process method, comprising: sending,by a charging system, a condition for triggering a charging request to apacket data network gateway, the condition comprises that a method for auser equipment to access a packet data network gateway changes;receiving, by a charging system from a packet data network gateway, thecharging request containing a type of a second method for the userequipment to access the packet data network gateway when the method fora user equipment to access the packet data network gateway has beenchanged from a first method to the second method; and performing, by thecharging system, based on the charging request, charging control overused service units in a first charging mode corresponding to the firstmethod for the user equipment to access the packet data network gateway,and reserving, by the charging system, service units for a service inthe case of the second method for the user equipment to access thepacket data network gateway based on a second charging modecorresponding to the second method for the user equipment to access thepacket data network gateway.
 7. The method of claim 6, wherein a methodfor a user equipment to access a packet data network changes comprisesat least one of: a change in a wireless access method, and a change in aserving node through which the user equipment accesses the packet datanetwork gateway.
 8. The method of claim 7, wherein: the change in thewireless access method includes a handover among a Wireless Local AreaNetwork, an Evolved UMTS Terrestrial Wireless Access Network and asecond generation mobile communication network/a third generation mobilecommunication network; and the serving node through which the userequipment accesses the packet data network gateway comprises a servinggateway or an evolved packet data gateway.
 9. The method of claim 8,wherein before sending the condition for triggering the charging requestcontained to the packet data network gateway, the method furthercomprises: receiving, by the charging system, an initial chargingrequest from the packet data network gateway, the initial chargingrequest including at least one of: a type of the first method for theuser equipment to access the packet data network gateway and requestedservice units in the case of the first method for the user equipment toaccess the packet data network gateway; wherein the condition fortriggering the charging request sent to the packet data network gatewayis contained in an initial charging request answer sent to the packetdata network gateway.
 10. The method of claim 8, wherein the receivedcharging request further comprises requested service units in a secondcharging mode corresponding to the second method for the user equipmentto access the packet data network gateway; and wherein reserving theservice units for a service in the case of the second method for theuser equipment to access the packet data network gateway based on asecond charging mode corresponding to the second method for the userequipment to access the packet data network gateway comprises: reservingthe service units for the service in the case of the second method forthe user equipment to access the packet data network gateway based on asecond charging mode corresponding to the second method for the userequipment to access the packet data network gateway according to therequested service units in the received charging request.
 11. The methodof claim 10, wherein the received charging request further comprises ahandover time when the method for the user equipment to access thepacket data network gateway is switched from the first method to thesecond method; wherein performing charging control over the used serviceunits in the first charging mode corresponding to the first method forthe user equipment to access the packet data network gateway is based ona reference point according to the handover time.
 12. The method ofclaim 8, further comprises: converting, by the charging system, theservices units from the first charging mode to the second charging modebased on the rating, if the first charging mode corresponding to thefirst method for the user equipment to access the packet data networkgateway is different from the second charging mode corresponding to thesecond method for the user equipment to access the packet data networkgateway.
 13. The method of claim 12, wherein: the first charging modecomprises at least one of: a flow-based mode, a time-based mode and anevent-based mode; the second charging mode comprises at least one of: aflow-based mode, a time-based mode and an event-based mode.
 14. Themethod of claim 10, further comprising: allocating service units for theservice in the case of the first method for the user equipment to accessthe packet data network gateway when receiving the initial chargingrequest from the packet data network gateway; wherein performingcharging control over the used service units in the first charging modecorresponding to the first method for the user equipment to access thepacket data network gateway comprises: compensating the user equipmentif the used service units in the first charging mode corresponding tothe first method for the user equipment to access the packet datanetwork gateway is less than the allocated service units to the service;and wherein reserving the service units for the service in the case ofthe second method for the user equipment to access the packet datanetwork gateway according to the requested service units comprises:determining service units to be allocated for the service in the case ofthe second method for the user equipment to access the packet datanetwork gateway based on the requested service units in the receivedcharging request, the used service units in the case of the first methodfor the user equipment to access the packet data network gateway, andaccount balance associated with the user equipment in a data base.
 15. Anetwork system, comprising: a packet data network gateway, configured toacquire a newly added condition for triggering a charging request and tomonitor based on the acquired condition if there is any change in amethod for a user equipment to access a packet data network gateway;send the charging request containing a type of a second method for auser equipment to access the packet data network gateway after thepacket data network gateway detects that the method for the userequipment to access the packet data network gateway is changed from afirst method to the second method; wherein the newly added condition fortriggering the charging request comprises the method for the userequipment to access the packet data network changes; and a chargingsystem, configured to add the new condition for triggering the chargingrequest; send the new condition for triggering the charging request tothe packet data network gateway; receive the charging request sent bythe packet data network gateway; perform, according to the chargingrequest, charging control over used service units in a first chargingmode corresponding to the first method for the user equipment to accessthe packet data network gateway; and reserve service units for a servicein the case of the second method based on a second charging modecorresponding to the second method for the user equipment to access thepacket data network gateway.
 16. The network system of claim 15, whereinthe method for the user equipment to access the packet data networkgateway is changed from a first method to the second method comprises atleast one of: a change in a wireless access method, the change in awireless access method includes a handover among a Wireless Local AreaNetwork, an Evolved UMTS Terrestrial Wireless Access Network and asecond generation mobile communication network/a third generation mobilecommunication network; and a change in a serving node through which theuser equipment accesses the packet data network gateway, the servingnode comprises a serving gateway or an evolved packet data gateway. 17.The network system of claim 16, wherein: the charging request sent bythe charging request unit to the charging system further comprisesrequested service units in the second charging mode corresponding to thesecond method for the user equipment to access the packet data networkgateway; and the charging system comprises: a condition setting unit,configured to add a new condition for triggering the charging requestand send the new condition for triggering the charging request to thepacket data network gateway; the new condition comprises the method forthe user equipment to access the packet data network gateway changes; areceiving unit, configured to receive the charging request sent by thepacket data network gateway; and a processing unit, configured toperform, based on the charging request received by the receiving unit,charging control over the used service units in the first charging modecorresponding to the first method for the user equipment to access thepacket data network gateway and to reserve service units for the servicein the case of the second method for the user equipment to access thepacket data network gateway based on the second charging modecorresponding to the second method for the user equipment to access thepacket data network gateway according to the requested service units.